GB2355793A

GB2355793A - A method of determining an itinerary or route

Info

Publication number: GB2355793A
Application number: GB0026235A
Authority: GB
Inventors: Laurent Mainard
Original assignee: Telediffusion de France ets Public de Diffusion; France Telecom SA
Current assignee: Telediffusion de France ets Public de Diffusion; Orange SA
Priority date: 1999-10-26
Filing date: 2000-10-26
Publication date: 2001-05-02
Also published as: GB0026235D0; FR2800184A1; FR2800184B1; DE10052934A1

Abstract

A method is described for determining an itinerary or route between a starting point 10 and an arrival 11 point on a network, such as a road network, the itinerary including traffic zones represented by curves on one or more graphs, each curve on a graph extending between two nodes of the graph and being completed with selection information, the itinerary being a recommended itinerary taking account of the various selection information. A particular arrangement described includes the steps of determining, as from the starting point and from the arrival point and by optimising a selection criterion, the input node on one of the graphs selected for its relevance to determine the itinerary, and the output node on the graphs, and then determining the part of the itinerary lying between the input and the output nodes which is optimised on the basis of the selection information completing the graph(s). The optimising criterion may be on the basis that the input node 23 and output node 24 are the closest to the starting point 10 and arrival point 11, respectively. The system (shown in fig.2) for carrying out the method may consist of a remote server 30 and a generally mobile terminal 40. Various claims relate to various aspects of the invention. For example, a claim is present which relates to a terminal in a system for transmitting an itinerary or route; another claim relates the server, etc.

Description

2355793 A METHOD OF DETERMINING AN ITINERARY OR ROUTE The present

invention relates to a method for determining an itinerary or route between a starting point and an arrival point in a network, for example a road system.

On-board navigation systems are known, which are associated with a system of vehicle location and which employ an on-board map system on a disc known as a CD-ROM, with which a user can pinpoint his destination and be guided "step-by-step" along an optimum itinerary according to the criteria that he has adopted and the information that is available in the vehicle.

However, these systems hardly, if at all, allow account to be taken of the true traffic conditions at the time when the user wishes to make use of these functions. To take these into account would presuppose that the navigation system has communication facilities, i.e. it can at least receive broadcast information, namely be capable of issuing a request calling for a personalised response.

Two families of system exist at the present time to provide the user with journey information in real time. The first is that based on a broadcast service, leaving it to the on-board terminal to calculate the itinerary on a graph composed of segments which are advised during the journey. The itinerary is broadcast, for example, using e.g. the communication protocol known as Alert +. The second completely delocalises the calculation of the itinerary, which is in this case entrusted to a remote server which transmits as complete a road map as possible. The communication protocol is e.g. the GATS protocol.

The problems with these two families of system will now be discussed. The first family presupposes the broadcasting, by one or other process, of a large quantity of journey time information intended for the completion of a graph. Normally, the number of journey times to be 2 broadcast is in the order of several thousand, in order to ensure routing through an urban network of average density. Besides, if the information is uncertain, or if there is no information for a part of the network, the on-board system must conform to a certain number of precise rules which are entrusted to the terminal manufacturer, rather than to the provider of the traffic information and/or the itinerary. Processes permitting travel time predictions to be integrated are similarly difficult to integrate within the restrictions imposed on broadcasting. The second family presupposes a form of itinerary transmission which, on the one hand, is capable of making use of a precise and complete database for managing the navigation system, which does not at present exist since map information suppliers can offer only limited compatibility between their data bases and, on the other hand, permit an itinerary to be precisely determined in order e.g. to accommodate it in a method employing short length information, such as that known under the name of SMS (Short Message System) which is 140 octaves in length rather than 5 or 6 as proposed under the GATS protocol.

A purpose of the present invention is to provide a method for determining an itinerary between a starting point and an arrival point in a network, e.g. a road system, that does not encounter the problems experienced under the previously proposed arrangements.

For this purpose, a process to be described below, by way of example in illustration of the invention is of the type for determining an itinerary lying between a starting point and an arrival point of a network, such as a road system, the itinerary including travel zones represented by curves on one or more graphs, each curve on a graph extending between two nodes on the graph and being provided with selection information, the itinerary being an advised itinerary taking account of the various selection information.

Features of an arrangement to be described below by way of example in illustration of the invention are that it includes determining, on the one hand, as from the starting point and by optimising the selection criteria, the input node on one of a number of graphs selected for their 3 relevance in order to determine the itinerary and, on the other hand, as from the arrival point and by optimising the selection criteria, the output node on the graphs, then determining the part of the itinerary lying between the input and the output nodes and optimising, on the basis of the selection information, the completion of the graph(s).

The stage for determining the input and the output nodes can be achieved independently, or otherwise, at the stage for determining the part of the itinerary between the input and the output nodes.

Another feature of an arrangement to be described by way of example in illustration of the invention is that the stage for determining the part of the itinerary between the input and the output nodes includes a stage for determining the input and the output nodes.

Arrangements to be described by way of example in illustration of the present invention also include a system for transmitting itineraries from a remote server to a terminal. In such a system, a terminal is provided for issuing a request passed on to the remote server and the server is enabled to reply to the request by transmitting an itinerary including travel zones represented by curves on one or more graphs, each curve on a graph extending between two nodes of the graph and being completed with selection information, including e.g. traffic information at the relevant time.

The itinerary transmitted by the server is an advised itinerary which takes account of various selection information at the time in question.

In one particular arrangement to be described by way of example in illustration of the invention, the terminal is able to issue a request for information which includes the starting point, the arrival point, and selection criteria, and the server is able to determine, from the starting point and the arrival point information, and by optimising the selection criteria, the input node on one of the graphs which are selected for their relevance in order to determine the itinerary and the output node on one of the graphs, to determine the part of the itinerary lying between the input and the output nodes and which is optimised on the basis of selection information completing the graph(s) and on the basis of the selection criteria, and to 4 transmit the itinerary to the terminal.

In one arrangement to be described by way of example in illustration of the invention, there is a system for transmitting itineraries, in which the terminal is able to determine, as from a starting point and an arrival point, and by optimising the selection criteria the input node, or the graphs selected for their relevance to determine the itinerary and the output node on the graphs, and to issue a request to the remote server, including the input node, the output node, the graphs selected for their relevance to determine the itinerary, and the or other selection criteria, and the server is able to determine the part of the itinerary lying between the input and the output nodes and optimised on the basis of the selection information completing the graph(s) and on the basis of the selection criteria and to transmit the itinerary to the terminal.

In another illustrative arrangement to be described below, by way of example, the nodes and/or the curves on each graph used in the system are specified as logical objects and in order to enable the itinerary to be transmitted to the terminal, it is specified by a succession of consecutive objects belonging to the, or to each relevant graph.

In yet another illustrative arrangement to be described, by way of example, the objects of the or of each relevant graph are grouped into sections where they show similarities, e.g. by appearing on the same graph, by order of length of travel time, or by type of road represented, etc.

Still further features of arrangements to be described by way of example in illustration of the invention include the use of the code for each curve on the graphs which are used for the system that corresponds to a reference number for the curves which converge on or depart from the same node, the itinerary transmitted then being specified by the succession of codes relative to the curves forming the itinerary, the use of the length of the code for a curve, which depends on the number of curves converging on or departing from the same node, that the part of the itinerary lying between two objects relating to the same lane is specified for its transmission by the code of the first of them and the number of objects separating them, that the objects and curves on each graph used by the system are respectively access points and intra-poles or inter-poles or trajectories as specified in the standard Alert +, that the server transmits, in addition to the itinerary, information with relevant local content, such as the state of the road traffic, road incidents, and useful addresses, etc., along and/or in the neighbourhood of the itinerary, that the request for an itinerary issued by the terminal additionally includes a version number for the graph(s) in a graphic database forming part of the terminal, that the itinerary includes an obsolescence indicator for the graphic database in relation to the graphic database used by the server, and that the server transmits a complete specification of the graphs used to each terminal.

Arrangements illustrative of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a graph linked from end to end between a starting point, for use in describing a method of operation, Fig. 2 illustrates a radio navigation system, and Figs 3 and 4 are graphs which illustrate where curves or nodes are specifically coded.

Referring to Fig. 1 there are shown a starting point 10, an arrival point 11 and a graph 20.

A graph, such as graph 20, is a set of nodes 21 each linked by curves 22. In practice, the nodes 21 can represent places, road junctions, crossroads, etc., and the curves may represent traffic lanes, such as road lanes or segments of a road, ring-road lanes, or section of ring roads, motorway lanes or sections of a motorway.

The curves are generally oriented, in a similar way to those shown in Figs. 1 and 3, i.e. one and the same road can be represented by two curves, the one for a lane in the direction of the traffic and the other for a traffic lane in the other direction.

However, it will be clear that this invention is also concerned with systems in which the curves are not so related, the two traffic lanes in a road with traffic travelling in both directions being represented in this case 6 by a single curve.

In a system, such as that in which the present invention may be employed, the nodes or curves are treated as if they were logical objects.

A system for transmitting itineraries, in a way which is suitable for use with the present invention, is shown in Fig. 2. It consists essentially of a permanent remote server 30 and a terminal 40 which, in the application being described, is generally mobile.

The remote server 30 includes a graphic database holding all the graphs that the system can process. It further includes an itinerary server 32 which, on the receipt of a request (see arrow R on the drawing) via the terminal 40, determines an itinerary for this terminal and transmits it to the terminal 40, (see arrow E on the drawing).

It may also possibly consist of a graph server 33 which, on request (see arrow RQ on the drawing) via the terminal 40, supplies (see arrow EQ on the drawing) the graph(s) required.

Terminal 40 includes essentially a processing unit 41 provided to transmit requests R and Ro and receive the data E and EC) concerning itineraries and graphs produced by the remote server 30. The graphs received from the server 30 are stored in a local graphic database 42. The terminal 40 also includes a map database serving essentially to represent itineraries only from itinerary data E received. This representation may be graphic on a appropriate screen, but it may be vocal or in some other form.

The functioning of the system represented in Fig. 2 will now be described.

From the terminal 40 there is issued a request R in which the coordinates or addresses of the starting point and of the arrival point on the itinerary to be specified are indicated, together with the itinerary selection criteria relating to one or more characteristics of the itinerary to be specified such as, for example, the fastest itinerary, the shortest itinerary in kilometres, etc.

On the basis of starting point 10 and the arrival point 11, the server 32 initially determines, on the one hand, the relevant graph(s) which will be 7 used to create the itinerary to be specified and, on the other, the input node on one of these graphs and the output node on one of these graphs. In Fig. 1, the input and output points are respectively designated 23 and 24.

The input and output nodes are the nodes on the selected graph(s) optimising the criteria for selecting the itinerary transmitted by the request R. For example they may be the nodes closest to starting point 10 and the arrival point 11.

It will be noted that, since the terminal 4 also possesses a graphic database 42, the unit 41 may similarly undertake these operations of selecting the relevant graphs and input and output nodes on one or other of these graphs. In that case, the request R may include coordinates of input and output nodes or of their identifier, an indication of the graphs selected, and the criteria for selecting the itinerary.

Subsequently, by optimising the criteria for selecting the itineraries contained in the request R, doing so in particular in relation to traffic or other information possessed by the units 32 along each of the curves constituting the selected graph(s), the unit 32 prepares the itinerary on the graph(s) selected.

It will be noted that, as described above, the operation of selecting the relevant graphs is undertaken independently of the operation for optimising the criteria and the preparation of the itinerary.

However, these two operations may be undertaken simultaneously in such a way that the input and output points on the selected graphs are determined taking account the preparation of the itinerary by optimising the criteria. Consequently, the criteria for selecting the itineraries can be more effectively optimised.

Following the execution of these two operations, the unit 32 issues the itinerary thus calculated for transmission to terminal 40 and, more particularly, to the processing unit 41.

On the basis of the particulars in Fig. 3, the curves (or alternatively the nodes) on each graph are specified as objects, e.g. numbe red 1 to N, N being the total number of objects on the graph (on Fig. 3, N = 23).

8 Consequently, the itinerary issued by the unit 32 is specified by the consecutive objects on the graph(s) on which it is included.

For example, in Fig. 3, the recommended itinerary is 12, 14, 15 and 19.

Certain objects may advantageously be grouped into sections where they show similarities, such as that they belong to the same graph, having the same order of travel time, or that they belong to the same lane, etc.

Consequently, in Fig. 3, curves 17,18,19 and 20 belong to the same section designated by the fact that e.g. they represent motorway lanes.

Another feature of an arrangement illustrative of the present invention is that the objects which constitute each graph are differently defined along the journey, the code for each object being relative to the previous object.

For example, each curve which is linked to a node on a graph is numbered. The itinerary is connected up, and in order to transmit an itinerary the number of the first curve or of the first node, is transmitted, followed by the number of the exit from each node. Fig. 4 shows a graph in which the curves or arcs are numbered in this way. For example in node 11, three curves number 1, 2, and 3, respectively are linked up. At node III, only two curves 1 and 2 are linked up.

The recommended itinerary is therefore coded 1, 1, 2, 3, 2, 2, 4.

It will be noted that the number of outputs to each node is much lower than the total number of curves on the graph and that, consequently, the coding of a node by the curve leading thereto requires fewer bits than the direct method. Globally, coding an itinerary on a graph also consequently requires fewer bits.

In addition, when specifying the graph in question itself, the number of bits required to code the number of the following curve can be associated with each curve at the output from a node. The length of an object code may therefore depend on the preceding object all along the itinerary. The result is a more or less optimum coding in the number of bits.

In Fig. 4, the number of bits required to code the output arcs or 2 curves from the nodes 1, 11, IV and V in binary form is two (2 = 4) while that 9 for the output curves at nodes 11, VI, VII and Vill is only one (2 2). The output codes at nodes 1, 11, IV and V therefore include the number of bits = 2 while those at the outputs of nodes 11, VI, V11 and Vill include the number 1.

In each case, in order to optimise the coding of the itinerary in the case of a succession of linear curves (represented e.g. by a road axis without intermediate exits), these curves are represented only by reference to the first of them and their number.

Consequently, in Fig. 4, nodes.IV, VII, Vill and V form a linear succession. They are coded e.g. as follows:

IV, 3, 3 which means: "exit 3 on node IV, 3 curves without ramifications".

According to another feature of an arrangement illustrative of the present invention, the graphs used in the system comply with the standard Alert +. More precisely, their nodes correspond to objects entitled "access points!' under this standard, and their curves correspond to objects called "intra-poles", "inter poles" or "trajectories" in this standard.

Another feature of an arrangement illustrative of the invention, is that the system additionally transmits data concerning the recommended itinerary, information with relevant local content, such as the state of road traffic, road incidents, useful addresses, etc., on and in the neighbourhood of the itinerary. For example, where the proposed itinerary passes along trunk roads an indication is given of the saturation situation of the traffic at periphery, or the location is given of filling stations along the route.

Yet another feature of an arrangement illustrative of the present invention, is that the request for an itinerary R made by unit 41 includes a version number for the graph(s) stored in the unit 42, and the itinerary contained in the reply E given by the unit 42 includes an obsolescence indicator for the on-board database contained in unit 42 in relation to the database used by the remote server 30.

The method for communicating the itinerary between the unit 32 and the unit 41 can be achieved by despatching short messages, such as those provided for a previously proposed system, under the system name SMS (Short Message System), which is defined in standards GTS GSM 11.11 andTGSGSM11.14. It will be noted that one of the advantages of the arrangements described in illustration of the invention is the extensive packing of data for the itineraries transmitted, which allows one or more itineraries to be sent on the same SMS.

In one particular arrangement illustrative of the invention, the system for communicating the itinerary is the GPRS system which is defined in standards EN 301 113 and EN 301 347.

The transmission system called UMTS (Universal Mobile Telecommunication Systems) could similarly be used.

It will be understood that, although particular arrangements, illustrative of the invention have been described by way of example, variations and modifications thereof, as well as other arrangements may be conceived within the scope of the appended claims.

Claims

1. A method for determining an itinerary or route between a starting point and an arrival point of a network, the itinerary including travel zones represented by curves on one or more graphs, each curve on the graph extending between two nodes on the same graph and being completed with selected information, the itinerary being a recommended itinerary taking account of the various selected information, including the steps of choosing, from amongst the graphs which can be processed, a set of relevant graphs to determine the itinerary, determining, as from the starting point and by optimising a selection criterion, a node on one of the graphs, called the input node, determining, as from the arrival point and by optimising a selection criterion, a node on one of the graphs, known as the output node, and determining that part of the itinerary lying between the input and the output nodes and optimised on the basis of the selection information completing the graphs.

2. A method as claimed in claim 1, in which the stages for determining the input node and the output node are implemented independently of the stage of determining the part of the itinerary between the input and the output nodes.

3. A method as claimed in claim 1, in which the stage of determining the part of the itinerary between the input and the output nodes includes the stage of determining the input and the output nodes.

4. A system for the transmission of itineraries from a remote server to a terminal, a terminal being provided to issue a request passed on to the server, such as a road network, and the server being provided to reply to the request by transmitting n itinerary including travel zones represented by curves on one or more graphs, each curve on a graph extending between two nodes of the graph and being completed with selected information, the itinerary being a recommended itinerary taking account of various selection criteria, in which the terminal is for issuing a request including the starting point, the arrival point and the selection criteria, and the server is for 12 choosing from amongst the graphs that the system can process a set of relevant graphs to determine the itinerary, to determine as from the starting point, by optimising the selection criteria, the output node on one of the graphs selected, and for determining the part of the itinerary lying between the input and the output nodes and optimised on the basis of selected information completing the graph(s) and on the basis of the said selection criteria and for transmitting the itinerary to the terminal.

5. A system for transmitting itineraries from a remote server to a terminal, the terminal being provided to issue a request to the server, and the server being provided to reply to the request by transmitting an itinerary including travel zones represented by curves on one or more graphs, each curve on a graph extending between two nodes of the graph and being completed with selected information, the itinerary being a recommended itinerary taWing account of various selection criteria, in which the terminal chooses from all the graphs that the system can process a set of relevant graphs for determining the itinerary, to be determined from the starting point by optimising the selection criteria, the input node on the graphs being selected and issuing a request to the remote server including for the input node, the output node, the graph selected for their relevance in determining the itinerary, and the said or other selection criteria, the server being provided to determine the part of the itinerary lying between the input and the output nodes and optimised on the basis of the selection information completing the graph(s), and on the basis of the selection criteria and for transmitting the itinerary to the terminal.

6. A system for transmitting itineraries from a remote server to a terminal as claimed in claim 4 or claim 5, in which the nodes and/or curves on each graph used in the system are specified as logical objects and in which the itinerary for them to be transmitted to the terminal, is specified by a succession of consecutive objects belonging to the or to each relevant graph.

7. A system as claimed in claim 6, in which the objects of the said or each relevant graph are grouped into sections where they show similarities, 13 e.g. by appearing on the same graph, by order of length of travel time, or by type of road represented, etc.

8. A system as claimed in claim 5 or claim 6 in which the code for each curve on the graphs that are used for the system corresponds to a reference number for the curves which converge on or depart from the same node, the itinerary transmitted being then specified by the succession of codes relative to the curves forming the itinerary.

9. A system as claimed in claim 8, in which the length of a code for a curve depends on the number of curves converging on or departing from the same node.

10. Asystem as claimed in anyone of claims 4to 8, inwhichthat part of the itinerary lying between two objects relating to the same lane is specified for its transmission by the code of the first of them and the number of objects separating them.

11. A system as claimed in any one of claims 4 to 10, in which the objects and the curves on each graph used by the system are respectively access points and intra-poles or inter-poles or trajectories as specified in the standard Alert +.

12. A system as claimed in any one of claims 4 to 11, in which the server transmits, in addition to the itinerary, information with relevant local content, such as the state of road traffic, road incidents, useful addresses, etc on and or in the neighbourhood of the said itinerary.

13. A system as claimed in any one of claims 4 to 12, in which the request for an itinerary issued by the terminal additionally includes a version number for the graph(s) in a graphic database forming part of the terminal and in which the itinerary includes an obsolescence indicator for the graphic database in relation to the graphic database used by the server.

14. A system as claimed in any one of claims 4 to 12, in which the server transmits a complete specification of the graphs used to each terminal.

15. A terminal in a system for transmitting itineraries including a server for recommended itineraries, the terminal being provided to issue a 14 request to the server and to receive, from the server in reply to the request, a recommended itinerary including travel zones represented by curves on one or more graphs, each curve of a graph extending between two nodes of the graph and being completed with selection information, in which the terminal determines, as from given starting and arrival points and by optimising selection criteria, the input node on the graphs selected for their relevance to determine the itinerary and the output node on one of the graphs, and issues the request to the remote server including the input node, the output node, the graph selected for relevance in determining the itinerary, and the said or other selection criteria.

17. A server for a system for transmitting itineraries provided to transmit to each terminal on the transmission system, at the request of the terminal, a recommended itinerary including travel zones represented by curves on one or more graphs, each curve on a graph extending between two nodes on the graph and being completed with selected information, in which the request from the terminal includes an input node and an output node on at least one graph, chosen for its relevance in determining the itinerary, and selection criteria, and in which the server determines the part of the itinerary lying between the input node and the output node on the basis of selection information completing the chosen graph(s), and on the basis of the selection criteria.

18. A request signal transmitted by a terminal in a system for transmitting itineraries to a server for recommended itineraries under the system, a recommended itinerary including travel zones represented by curves on one or more graphs, each curve on a graph extending between two nodes of the graph and being completed with selection information, including an input node and an output node on at least one graph selected for its relevance in determining the itinerary, and the selection criteria.

19. Graphs used in a system for transmitting itineraries as claimed in any of claims 4 to 14, the system being provided with a server transmitting a recommended itinerary to a terminal at its request, including travel zones represented by curves on one or more graphs, each curve on a graph extending between two nodes of the graph and being completed with selection information, in which the nodes and/or curves are classified as logical objects.

20. A graph as claimed in claim 19, in which the objects of the or of each relevant graph are grouped into sections in which they show similarities, e.g. by appearing on the same graph, by order of length of travel time, or by type of road represented, etc 21. A graph as claimed in claim 19 or claim 20, in which the code for each curve on the graphs that are used by the system corresponds to a reference number for the curves which converge on or depart from the same node.

22. A graph as claimed in claim 21, in which the length of the code for a curve depends on the number of codes converging on or departing from the same code.

23. A graph as claimed in any one of claims 19 to 22, in which the objects and curves on each graph used by the system are respectively access points and intra-poles or inter-poles as specified in the standard Alert +.

24. A signal for a recommended itinerary transmitted by a server for a system for transmitting itineraries to a terminal on the system at the request of the terminal, the transmission system conforming to one at least of claims 4 to 14, the recommended itinerary including travel zones represented by curves on one or more graphs, each curve on a graph extending between two nodes of the graph and being completed with selection information, in which the itinerary is specified by a succession of consecutive logical objects representing nodes and/or curves respectively on the or on each relevant graph between an input node and an output node specified in the request issued by terminal.

25. A signal for an itinerary as claimed in claim 24, in which each logical object is a code allocated to each curve on graphs that are used by the system, the code corresponding to a reference number for the curves that converge on or depart from the same node, the itinerary transmitted 16 being then specified by the succession of codes relative to the curves forming the itinerary.

26. A signal for an itinerary as claimed in claim 25, in which the length of a code for a curve depends on the number of curves converging on or departing from the same node.

27. A signal for an itinerary as claimed in any one of claims 24 to 26, in which a part of the itinerary lying between two objects relating to the same lane is specified for its transmission by the code of the first of them and the number of objects separating them.

28. A method for determining an itinerary or route as claimed in claim 1 substantially as described herein with reference to the accompanying drawings.

29. A system for the transmission of itineraries as claimed in claim 4 substantially as described herein with reference to the accompanying drawings.

30. A terminal in a system for transmitting itineraries as claimed in claim 5 substantially as described herein with reference to the accompanying drawings.

31. A server for a system for transmitting itineraries as claimed in claim 17 substantially as described herein with reference to the accompanying drawings.

32. A request signal transmitted by a terminal in a system for transmitting itineraries to a server as claimed in claim 18 substantially as described herein with reference to the accompanying drawings.

33. Graphs used in a system for transmitting itineraries as claimed in claim 19 substantially as described herein with reference to the accompanying drawings.

34. A signal for a recommended itinerary as claimed in claim 24 substantially as described herein with reference to the accompanying drawings.